Effect of Nb concentration on the structure, mechanical, optical, and electrical properties of nano-crystalline Ti1−x Nb x N thin films

The structure, mechanical, optical, and electrical properties of Ti1−x Nb x N thin films, 0 ≤ x ≤ 1, are reported. The films were deposited onto polycrystalline nuclear grade 316LN stainless steel substrate by radio frequency reactive magnetron sputtering in 100% N2 plasma. X-ray diffraction results revealed that Nb is soluble in TiN up to x = 0.77. From x = 0.26 to x = 0.77, these films stabilized in rock salt structure with (111) orientation. The hardness and Young’s modulus increased, whereas electrical resistivity decreased with an increase in the Nb concentration in the films. The highest value of hardness and Young’s modulus were 31 and 320 GPa, respectively, for x = 0.77, at which the value of the lowest resistivity of 56 μΩ-cm was measured. The films showed a broad reflectance band, with a minimum in reflectance that shifted to shorter wavelengths as a function of increasing x. The reflectance band extended from the ultraviolet (~250 nm) to the visible region (~750 nm) and the position of the reflectance shifted from 2.33 to 3 eV with an increase in x from 0 to 0.77.